ITEM-IN-MESSAGE FORMAT                                     21 Feb 12
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                                                              WB4APR

21 Feb 12 updated to mention the new MESSAGE OBJECT function
30 Oct 08 added options for Sending and Reading-the-mail
07 Oct 08 updated

The original ITEM-in-MSG format was designed to provide a 
mechanism for a station in message contact with someone anywhere in 
the APRS system to be able to exchange position data, not only of 
his own station, but also of any objects he would like the other 
station to see.  For example.  This would be used by the AVRS engine
to send FREQUENCY OBJECT to a called station to have him QSY to 
receive the voice call.  See http://aprs.org/avrs.html

Do not confuse this with the MESSAGE OBJECT function which is a
backwards compatible way for any existing radio to be used to send
a MESSAGE OBJECT to a special OBJECT server where it is converted
to an object on the APRS-IS.  See http://aprs.org/aprs12/msg-obj.txt

The format for ITEM-in MSG is simply an ITEM format inserted in the 
message text field..  The ITEM format is defined as:

)NAME!DDMM.mmN/DDDMM.mmW$text.....

* Where the first character is the ")"
* Then a variable length object name (up to 9 bytes)
* Then the usual FIXED position format beginning with a !
  and followed by LAT/LONG and SYMBOL 
* Text is the variable length field which may contain any of the
  other APRS formatted data:

  CSE/SPD data  CCC/SSS/
  PHG data      PHGphgd
  FREQUENCY     FFF.FFFMHz
  DF data       CSE/SPD/BRG/NRQ etc
  other         any other valid fields in a position report

ACKS: The ITEM-IN-MESSAGE message is transmitted like any other 
message including a message line number on the end.  Similarly it 
is acked like any other message.  If the ITEM is intended for a 
local or APRS-IS wider audience, then the ITEM might be sent to 
a generic callsign so that it is not acked but allowed to retry 
the typical 5 times to improve the reliability 
of receipt by all parties.

DISPLAY:  On receipt, if the message contains the above ITEM format, 
then the ITEM and position information is copied to the STATION/
OBJECT list and displayed on the map. 

RETENTION: If the client can edit and send its own objects from the 
STATION list, then it is OK to not retain a copy of the incoming 
ITEM-in-MSG where it will just take up room.  On the other hand,
if the client is unable to originate objects, then a copy of the 
incoming ITEM-in-MSG should be retained in the MESSAGE list for 
future editing.  

SENDER's CALLSIGN:  The callsign of the sender should always be
retained and displayed associated with this ITEM/OBJECT  just like
any other object.

SEND OPTION:  Another option is in the MESSAGE MENU.  There can be 
a menu item there to allow the sending station to select any object 
or station in his station list, and (after editing) send it as an 
ITEM-in-MSG to another party.

READING-THE-MAIL:  Another option is on receipt. Even if a message
is not to this station, if an ITEM-IN-MSG format is detected while
monitoring the channel, such an ITEM should be considered general
positional info and should be captured and plotted on the map.

Bob, WB4APR